Nowadays, HDMI (high definition multimedia interface) technology is commonly used in televisions. A television may include multiple HDMI interface connectors that are used to connect multiple multimedia devices (e.g., STB (set top box) devices, Blu-ray or DVD players, videogame consoles, etc.) to the television. In use, a user may select only one or at most two multimedia devices (e.g., in a case that the PIP/PAP (picture-in-picture or picture-and-picture) function is used) to provide multimedia content for watching at a time. However, when the user changes the content source that provides the multimedia content from one multimedia device to another multimedia device, he or she may forget to have the multimedia device that originally served as the content source turned off or put on standby, resulting in unnecessary and undesired power consumption.